Catechism of the Catholic Church §214 — excerpt
God, "HE WHO IS", revealed himself to Israel as the one "abounding in steadfast love and faithfulness". These two terms express summarily the riches of the divine name.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.